Controlled adhesion remains an unmet technological need. For example, for over twenty years the robotics field has tried to invent a reliable form of controlled adhesion on a wide range of substrates for wall crawling robots, without success. Success in controlled adhesion can be defined by a technology that is: controllable, reliable, and robust enough to work on a sufficient range of everyday wall and natural materials, and those encountered under real environmental conditions, such as wet or dusty surfaces, highly sloped surfaces, or slippery surfaces.
The existing technologies, many of which are still in the lab and not in commercial production, marked for wall crawling fail to provide the full range of these capabilities. Chemical adhesives are always “on.” While they require no energy to perch, robots that employ chemical adhesive clamping technologies require a lot of energy to climb and traverse horizontally (requiring more batteries and weight), fighting the adhesion which cannot be switched off. Chemical adhesive technologies can also attract dust and other debris that quickly reduce their effectiveness. Suction (active or passive) works effectively only on smooth surfaces. Also, conventional suction cups suffer from leaks and cannot manage dusty surfaces. Mechanical claws only work on very rough or penetrable surfaces and often leave damaging marks. Synthetic gecko-like skin can become easily damaged or befouled after repeated use (as few as five cycles), and does not work on wet surfaces.
Controlled adhesion is also useful outside of robotics. Robust devices and methods to provide adhesion would be beneficial.